The parents of a Georgia teenager found dead at school inside a rolled up gym mat have filed a new wrongful death lawsuit in federal court.

Classmates at Lowndes High School in Valdosta found 17-year-old Kendrick Johnson's body inside an upright mat Jan. 11, 2013. Investigators concluded he died in a freak accident, but Johnson's parents say someone killed him.

The lawsuit filed Aug. 17 in U.S. District Court by Kenneth and Jacquelyn Johnson names 39 defendants. It echoes a suit they filed last year and later dropped in a state court, alleging that classmates killed their son and law enforcement and school officials covered up the crime.

A Superior Court judge has ruled Johnson's parents must pay attorney fees for people they sued previously, but hasn't determined how much.